At the end of the day Monday, approximately 18 pints of blood had been donated by 18 people who gave during a drive at Masonic Pathways in Alma, according to volunteer Lynne Ludy on Tuesday.

There are two main reasons for the shortage nationwide, she said.

“The holiday season means that many regular donors are traveling or busy with visitors and are unable to fit the hour it takes to donate into their busy schedules,” Ludy said.

Weather, travel conditions and seasonal sickness such as the flu are the overall second reason why there is a shortage.

“If the roads are bad or the temperature is very low, people hunker down and stay home instead of coming out to donate,” Ludy said. “In addition, drives occasionally have to be cancelled because staff and equipment are unable, because of road conditions, to travel to the drive sites.”

According to the Red Cross, 550 blood drives across the U.S. were cancelled this month due to weather, causing more than 16,500 blood and platelet donations to go uncollected through last week.

“Blood and platelet donations are currently being distributed to hospitals faster than they are coming in,” said Clifford Numark, senior vice president at Red Cross Blood Services, in a news release. “Donors are critically needed to restock the shelves for patients in their community as well as areas where donors are unable to give due to inclement weather.”

Type O blood, which can be transfused to any recipient, is the most requested by hospitals and is often in short supply, according to Ludy.

Every day, no matter the weather, the Red Cross must collect more than 13,000 blood and platelet donations to meet the needs of patients, the release stated.

The following is a list of upcoming Red Cross blood drives in the county: